Stackable cover members for containers are well known and may be employed on either the top or bottom of the container. However, such prior art cover members do not provide a simple seal arrangement which can withstand excess internal pressure which may buildup within the container. Accordingly, if an excess pressure occurs in the container, even a short exposure of the cover member to such excess pressure may result in weakening or complete loss of the internal seal, which would result in complete damage to the entire package. In addition, such prior art stackable members do not provide stacking without nesting. Accordingly, it is an object of the present invention to provide a stackable cover member for a container which overcomes one or more of the aforesaid problems. Specifically, it is within the contemplation of the present invention to provide a stackable cover member which avoids weakening of the internal seal between the cover member and container which is typically caused by excess internal pressure within the container.
It is a further object of the present invention to provide a stackable cover member for a container which includes a simple and secure internal seal arrangement and which may be stacked without nesting.